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IHierarchicalEnumerable.GetHierarchyData Method

Returns a hierarchical data item for the specified enumerated item.

Namespace:  System.Web.UI
Assembly:  System.Web (in System.Web.dll)

IHierarchyData GetHierarchyData(
	Object enumeratedItem
)

Parameters

enumeratedItem
Type: System.Object
The Object for which to return an IHierarchyData.

Return Value

Type: System.Web.UI.IHierarchyData
An IHierarchyData instance that represents the Object passed to the GetHierarchyData method.

Typically, clients that use IHierarchicalEnumerable collections retrieve an IEnumerator object by calling the GetEnumerator method, then iterate through the enumeration and call the GetHierarchyData method on each enumerated item to retrieve an IHierarchyData object.

The following code example demonstrates how an ASP.NET hierarchical data-bound control uses an IHierarchyData object in a recursive data-binding method. The items in an IHierarchicalEnumerable object are enumerated, and for each an IHierarchyData object is retrieved using the GetHierarchyData method. Finally, the HasChildren property is checked to determine whether recursion is necessary. This code example is part of a larger example provided for the HierarchicalDataBoundControl class.


private void RecurseDataBindInternal(TreeNode node, 
    IHierarchicalEnumerable enumerable, int depth) {                                    

    foreach(object item in enumerable) {
        IHierarchyData data = enumerable.GetHierarchyData(item);

        if (null != data) {
            // Create an object that represents the bound data
            // to the control.
            TreeNode newNode = new TreeNode();
            RootViewNode rvnode = new RootViewNode();

            rvnode.Node = newNode;
            rvnode.Depth = depth;

            // The dataItem is not just a string, but potentially
            // an XML node or some other container. 
            // If DataTextField is set, use it to determine which 
            // field to render. Otherwise, use the first field.                    
            if (DataTextField.Length > 0) {
                newNode.Text = DataBinder.GetPropertyValue
                    (data, DataTextField, null);
            }
            else {
                PropertyDescriptorCollection props = 
                    TypeDescriptor.GetProperties(data);

                // Set the "default" value of the node.
                newNode.Text = String.Empty;                        

                // Set the true data-bound value of the TextBox,
                // if possible.
                if (props.Count >= 1) {                        
                    if (null != props[0].GetValue(data)) {
                        newNode.Text = 
                            props[0].GetValue(data).ToString();
                    } 
                }
            }

            Nodes.Add(rvnode);                    

            if (data.HasChildren) {
                IHierarchicalEnumerable newEnumerable = 
                    data.GetChildren();
                if (newEnumerable != null) {                            
                    RecurseDataBindInternal(newNode, 
                        newEnumerable, depth+1 );
                }
            }

            if ( _maxDepth < depth) _maxDepth = depth;

        }
    }
}


.NET Framework

Supported in: 4, 3.5, 3.0, 2.0

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.
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